1. Field of the Invention
The present invention relates generally to the field of tooling used in the maintenance of oil well pumping equipment, and more particularly pertains to a hand tool for safely lifting and replacing the unitized jaw assembly in power sucker rod tongs.
2. Background of the invention
In certain oil wells the oil is recovered from underground reservoirs by means of a pump-jack installed at the surface and connected by a string of sucker rods to a pump valve located at the bottom of the oil well. The sucker rods are rigid rods threaded end-to-end to make up a string of the necessary length, depending on the depth of the particular oil well. This rigid string transmits up-and-down reciprocating motion from the pump jack to the underground pump valve. Each sucker rod is a round bar of steel which is upset at each end to form a square torquing shoulder section with a male threaded end. A coupling with mating female threads at each end is screwed to the ends of two adjacent sucker rods to make a rigid joint between them. This process is repeated to generate a string of the necessary length.
From time to time it is necessary to remove and reinstall the string of sucker rods. This operation is typically carried out with the aid of a hydraulically driven power sucker rod tongs. The power tongs includes a set of jaws which grip and rotate the sucker rod joint while a fixed wrench keeps a second, lower sucker rod joint from turning, thus providing the torque needed for turning the upper joint. The leading manufacturer of power sucker rod tongs is Byron Jackson Co., now BJ VARCO, which company designed and developed this tool more than twenty years ago. The direction of rotation of the jaws in the tongs, clockwise or counterclockwise, is controlled by a valve system which directs hydraulic pressure to a hydraulic motor which turns a bull gear in the center of the tool in one direction or the other. A unitized jaw assembly fits into the bull gear and has a latch mechanism which will permit rotation of the bull gear in only one direction or another depending on which side of the jaw assembly is facing up in the power tongs. With the unitized jaw assembly placed with one specific side up in the bull gear, the latch mechanism of the jaw assembly will permit only clockwise rotation of the bull gear. If the unitized jaw assembly is now removed, turned upside down and reinstalled into the bull gear, it will permit counterclockwise rotation. The unitized jaw assembly also has a small key on the outside, which must engage into a mating slot in the bull gear for proper installation and operation. If the unitized jaw assembly is not properly aligned, it will not permit the power sucker rod tongs to function. In addition, the bull gear has to be aligned with a sucker rod entry slot in the body of the power sucker rod tongs before the unitized jaw assembly can be removed or installed.
Inasmuch as the power sucker rod tongs are an old tool design, an operator normally uses his fingers to grasp and directly handle the unitized jaw assembly whenever its removal or replacement is needed. For this purpose finger holes are formed on both sides, top and bottom, of the unitized jaw assembly to provide a grip for the operator's fingers. Over the years, a number of operators have lost their fingers during this procedure, because the power tongs might start rotation while the operator's fingers are still engaged in the finger holes of the unitized jaw assembly. In response to these injuries, OSHA has required that the power sucker rod tongs must be disengaged from the hydraulic power source before removal or installation of the unitized jaw assembly is made. Workover rigs, which use power sucker rod tongs to handle the removal and replacement of sucker rod strings in an oil well, are very dirty and messy work places. Disconnected hydraulic fittings to the power sucker rod tongs are likely to get dirty, with contamination entering the hydraulic system, resulting in a shortened life of the hydraulic tools. Hydraulic oil may also spill and create slippery and dangerous work surfaces on the rig floor. If the bull gear is not properly aligned with the entry slot in the body of the power tongs, it becomes necessary to reconnect the hydraulic lines so that the bull gear can be rotated slightly. The hydraulic lines must then be again disconnected, so that the fingers of the operator can again try to remove the unitized jaw assembly. If the latter still does not come loose, the cycle is repeated until the bull gear is properly oriented. This problem is compounded by the need to orient the external key on the unitized jaw assembly with the keyway in the bull gear. All told, the removal and/or installation of the unitized jaw assembly can be a time consuming and dangerous operation with possible serious injury to the fingers and hands of the operator.
A continuing need exists for a safe and simple-to-use tool which will assist the operator in the removal and or installation of the unitized jaw assembly in power sucker rod tongs while maintaining the hands and fingers of the operator at a safe distance and protected from the moving parts of the power tongs, and thereby to avoid the need for disconnecting the hydraulic lines to the power tongs during this operation. This applicant is not aware of any existing tool suited to this purpose.